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|
/*
* Copyright 2011-2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "rand_lcl.h"
/*
* Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
*/
/*
* Get entropy from the existing callback. This is mainly used for KATs.
*/
static size_t get_entropy(DRBG_CTX *dctx, unsigned char **pout,
int entropy, size_t min_len, size_t max_len)
{
if (dctx->get_entropy != NULL)
return dctx->get_entropy(dctx, pout, entropy, min_len, max_len);
/* TODO: Get from parent if it exists. */
return 0;
}
/*
* Cleanup entropy.
*/
static void cleanup_entropy(DRBG_CTX *dctx, unsigned char *out, size_t olen)
{
if (dctx->cleanup_entropy != NULL)
dctx->cleanup_entropy(dctx, out, olen);
}
/*
* The OpenSSL model is to have new and free functions, and that new
* does all initialization. That is not the NIST model, which has
* instantiation and un-instantiate, and re-use within a new/free
* lifecycle. (No doubt this comes from the desire to support hardware
* DRBG, where allocation of resources on something like an HSM is
* a much bigger deal than just re-setting an allocated resource.)
*
* The DRBG_CTX is OpenSSL's opaque pointer to an instance of the
* DRBG.
*/
/*
* Set/initialize |dctx| to be of type |nid|, with optional |flags|.
* Return -2 if the type is not supported, 1 on success and -1 on
* failure.
*/
int RAND_DRBG_set(DRBG_CTX *dctx, int nid, unsigned int flags)
{
int ret = 1;
dctx->status = DRBG_STATUS_UNINITIALISED;
dctx->flags = flags;
dctx->nid = nid;
switch (nid) {
default:
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
return -2;
case 0:
/* Uninitialized; that's okay. */
return 1;
case NID_aes_128_ctr:
case NID_aes_192_ctr:
case NID_aes_256_ctr:
ret = ctr_init(dctx);
break;
}
if (ret < 0)
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
return ret;
}
/*
* Allocate memory and initialize a new DRBG. The |parent|, if not
* NULL, will be used to auto-seed this DRBG_CTX as needed.
*/
DRBG_CTX *RAND_DRBG_new(int type, unsigned int flags, DRBG_CTX *parent)
{
DRBG_CTX *dctx = OPENSSL_zalloc(sizeof(*dctx));
if (dctx == NULL) {
RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
return NULL;
}
dctx->parent = parent;
if (RAND_DRBG_set(dctx, type, flags) < 0) {
OPENSSL_free(dctx);
return NULL;
}
return dctx;
}
/*
* Uninstantiate |dctx| and free all memory.
*/
void RAND_DRBG_free(DRBG_CTX *dctx)
{
if (dctx == NULL)
return;
ctr_uninstantiate(dctx);
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, dctx, &dctx->ex_data);
/* Don't free up default DRBG */
if (dctx == RAND_DRBG_get_default()) {
memset(dctx, 0, sizeof(DRBG_CTX));
dctx->nid = 0;
dctx->status = DRBG_STATUS_UNINITIALISED;
} else {
OPENSSL_cleanse(&dctx->ctr, sizeof(dctx->ctr));
OPENSSL_free(dctx);
}
}
/*
* Instantiate |dctx|, after it has been initialized. Use |pers| and
* |perslen| as prediction-resistance input.
*/
int RAND_DRBG_instantiate(DRBG_CTX *dctx,
const unsigned char *pers, size_t perslen)
{
size_t entlen = 0, noncelen = 0;
unsigned char *nonce = NULL, *entropy = NULL;
int r = 0;
if (perslen > dctx->max_pers) {
r = RAND_R_PERSONALISATION_STRING_TOO_LONG;
goto end;
}
if (dctx->status != DRBG_STATUS_UNINITIALISED) {
r = dctx->status == DRBG_STATUS_ERROR ? RAND_R_IN_ERROR_STATE
: RAND_R_ALREADY_INSTANTIATED;
goto end;
}
dctx->status = DRBG_STATUS_ERROR;
entlen = get_entropy(dctx, &entropy, dctx->strength,
dctx->min_entropy, dctx->max_entropy);
if (entlen < dctx->min_entropy || entlen > dctx->max_entropy) {
r = RAND_R_ERROR_RETRIEVING_ENTROPY;
goto end;
}
if (dctx->max_nonce > 0 && dctx->get_nonce != NULL) {
noncelen = dctx->get_nonce(dctx, &nonce,
dctx->strength / 2,
dctx->min_nonce, dctx->max_nonce);
if (noncelen < dctx->min_nonce || noncelen > dctx->max_nonce) {
r = RAND_R_ERROR_RETRIEVING_NONCE;
goto end;
}
}
if (!ctr_instantiate(dctx, entropy, entlen,
nonce, noncelen, pers, perslen)) {
r = RAND_R_ERROR_INSTANTIATING_DRBG;
goto end;
}
dctx->status = DRBG_STATUS_READY;
dctx->reseed_counter = 1;
end:
if (entropy != NULL && dctx->cleanup_entropy != NULL)
dctx->cleanup_entropy(dctx, entropy, entlen);
if (nonce != NULL && dctx->cleanup_nonce!= NULL )
dctx->cleanup_nonce(dctx, nonce, noncelen);
if (dctx->status == DRBG_STATUS_READY)
return 1;
if (r)
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, r);
return 0;
}
/*
* Uninstantiate |dctx|. Must be instantiated before it can be used.
*/
int RAND_DRBG_uninstantiate(DRBG_CTX *dctx)
{
int ret = ctr_uninstantiate(dctx);
OPENSSL_cleanse(&dctx->ctr, sizeof(dctx->ctr));
dctx->status = DRBG_STATUS_UNINITIALISED;
return ret;
}
/*
* Mix in the specified data to reseed |dctx|.
*/
int RAND_DRBG_reseed(DRBG_CTX *dctx,
const unsigned char *adin, size_t adinlen)
{
unsigned char *entropy = NULL;
size_t entlen = 0;
int r = 0;
if (dctx->status != DRBG_STATUS_READY
&& dctx->status != DRBG_STATUS_RESEED) {
if (dctx->status == DRBG_STATUS_ERROR)
r = RAND_R_IN_ERROR_STATE;
else if (dctx->status == DRBG_STATUS_UNINITIALISED)
r = RAND_R_NOT_INSTANTIATED;
goto end;
}
if (adin == NULL)
adinlen = 0;
else if (adinlen > dctx->max_adin) {
r = RAND_R_ADDITIONAL_INPUT_TOO_LONG;
goto end;
}
dctx->status = DRBG_STATUS_ERROR;
entlen = get_entropy(dctx, &entropy, dctx->strength,
dctx->min_entropy, dctx->max_entropy);
if (entlen < dctx->min_entropy || entlen > dctx->max_entropy) {
r = RAND_R_ERROR_RETRIEVING_ENTROPY;
goto end;
}
if (!ctr_reseed(dctx, entropy, entlen, adin, adinlen))
goto end;
dctx->status = DRBG_STATUS_READY;
dctx->reseed_counter = 1;
end:
if (entropy != NULL && dctx->cleanup_entropy != NULL)
cleanup_entropy(dctx, entropy, entlen);
if (dctx->status == DRBG_STATUS_READY)
return 1;
if (r)
RANDerr(RAND_F_RAND_DRBG_RESEED, r);
return 0;
}
/*
* Generate |outlen| bytes into the buffer at |out|. Reseed if we need
* to or if |prediction_resistance| is set. Additional input can be
* sent in |adin| and |adinlen|.
*/
int RAND_DRBG_generate(DRBG_CTX *dctx, unsigned char *out, size_t outlen,
int prediction_resistance,
const unsigned char *adin, size_t adinlen)
{
int r = 0;
if (dctx->status != DRBG_STATUS_READY
|